Lockstitch sewing machine



' July 28, 1936.

J. GOULDBOURN ET AL LOCI/(STITCH SEWING MACHINE Filed Jan. 12, 1934 7Sheets-Sheet l Wflness 1 /6.

I July 28, 1936. J. GOULDBOURN ET AL 9,

' LOCI STITCH SEWING MACHINE Filed Jan. 12, 1934 7 Sheets-Sheet 2 July28, 1936; J. GOULDBOURN E-f AL 2,049,369

\ LOCKSTITCH SEWING MACHINE Filed Jan. 12, 1934 '7 Sheets-Sheet 5 July28, 1936.

J. GOULDBOU RN ET AL LOCKSTITCH SEWING MACHINE '7 Sheets-Sheet 4 FiledJan. 12, 1934 25 9 rTa y 1936. J. GOULDBOURN ET AL LOQKSTITCH SEWINGMACHINE Filed Jan. 12, 1954 7 Sheets-Sheet 5 y 28, 9 J. GOULDBOURN ET ALLOCKSTITCH SEWING MACHINE Filed- Jan. 12, 1934 7 Sheets-Sheet 6 yz 1936-V J. GOULDBOURN ET AL 2,049,369

LOCKS-TITCH SEWING MACHINE Filed Jan. 12,, 1934 7 Sheets-Sheet 7Patented July 28, 1936 UNETED' STATES PATENT OFFICE Leicester, England,

and Nathan Freeman Hopkins, Rockland, Mass, assignors to United ShoeMachinery Corporation, Paterson, N. J., a corporation of New JerseyApplication January 12, 1934, Serial No. 706,444 In Great BritainFebruary 2, 1933 13 Claims.

This invention is concerned with improvements in or relating to sewingmachines and is particularly, but by no means exclusively, concernedwith sewing machines suitable for oper- 5..',-ating on thick stubbornmaterials such as leather.

In co-pending application of Joseph Gouldbourn, Frank B. Keall andThomas A. Kestell Serial No. 688,480 filed September '7, 1933, there 10is disclosed a machine for sewing the outsoles of welted boots or shoesto their welts by a lockstitch seam, which machine has thread handlingand work feeding instrumentalities arranged to enable the machine tooperate smoothly at a lfigrelatively high speed.

While'such a machine as is last referred to has been found to elfectvery good stitching at relatively high speeds we have found it possiblestill further to improve the efliciency of the 20 stitching operation ofthe machine by modifying the action of certain of the thread handlinginstrumentalities. I

In a machine arranged as disclosed in the prior specification abovereferred to a rotary 25 shuttle of the type disclosed in the co-pendingapplication of Joseph Gouldbourn and Thomas A. Kes-tell Serial No.630,044 filed August 23, 1932 upon which Patent No. 1,991,456 issuedFebruary 19, 1935 is used and although such a g 30 shuttle is found tooperate satisfactorily in looping the needle thread over the shuttlethread it is found, when using such a shuttle, that uniform results inthe setting of the stitch locks formed between the needle and shuttlethreads within 35 the work may not in some circumstances always beobtained.

Such a shuttle as is above referred to has a nose projecting downwardlyfrom the bobbin case and the thread is arranged to pass out of .,thebobbin case through a hole in the end of the nose. The bobbin case isallowed to vibrate somewhat about the axis of the bobbin during therunning of the machine to allow forward limbs of the loops of needlethread lifted over 45 the shuttle to pass between the forward side ofthe bobbin case and a relatively fixed ridge which engages loosely in aV-shaped groove formed in the front wall of the bobbin case. The saidvibration of the bobbin case is effected 50 by the friction between thebobbin case and the rotating shuttle case, and by the action of theforward limb of the loop of needle thread in passing between the saidfixed ridge and the sides of the V-shaped groove in the bobbin case. 55:The vibration of the bobbin case is found to vary in extent duringdifferent cycles of the machine and therefore imparts an oscillatingmovement of inconstant amount to the said nose which, as it moves to andfro, causes small and inconstant amounts of thread to be drawn 5 ofi thebobbin in successive machine cycles, which inconstant amounts are usedup in the formation of successive stitches.

Furthermore, since the movements of the said nose are only controlled ina non-positive manner, it is liable to happen during the actual settingof successive stitch locks within the work that the nose, during thesetting of one stitch lock, may be rising away from the work andtherefore exerting a tension on the shuttle thread and pullingadditional thread off the bobbin and, during the setting of the nextstitch lock, may descend towards the work and relieve somewhat thetension on the shuttle thread and pay out additional shuttle thread.Therefore, there is a tendency for the actual lengths of threadextending from the nose to the work during the setting of successivestitch locks to vary and also for the tensions in the shuttle thread tovary at these times. i

We have found that relatively slight variations in the slackness ortautness of the shuttle thread during successive stitch-settingoperations causes relatively great differences in the depths to whichthe successive stitch-locks can be set within the work by a uniformtension exerted on the needle thread. It is one of the objects of thepresent invention to avoid or at least minimize variations in theslackness or tautness of the shuttle thread during successivestitch-setting operations. The action of drawing the shuttle thread onto the work by the loop of needle thread after the latter has passedover the shuttle, acting as it does in the machine disclosed in theprior specification first mentioned against the action of a tensiondevice on the bobbin case, imposes an appreciable strain on the needlethread and causes substantial reeving of the two threads round eachother which is likely to weaken the threads and mar the appearance ofthe threads in the finished stitch.

In a particular illustrative embodiment of the present inventionhereinafter described, the tendency for the threads to reeve around eachother as the shuttle thread is being drawn down on to the work by theneedle thread is minimized by arranging the bobbin case in the shuttlein such a manner that as the needle thread acts to draw the shuttlethread against the work, the bobbin ating these trains of mechanism atsuch times" details of the'shuttle driving mechanism; Figure willapproach bodily towards the work and will provide a slackness, ofconstant amount, in the thread extending from the bobbin to'the work.Thus, when the needle thread acts to draw the slackened shuttle threaddown on to the work it will be able to laythe shuttle thread easilyagainst the work without" causing excessive reeving between the threadssince during at least part of the time when the shuttle thread is beinglaid against the work the movement of the shuttle; thread towards thework will not be restrained,

by the tension device on the bobbin case.

In the machine disclosed in the prior specification first mentionedupper and lower thread looking devices are used which operatealternately to grip the needle thread between the thread supply and athread measuring device and between the thread measuring device and thelooper respectively at certain times in the machine cycle.

These devices are so operated in that machine that almost as soon as oneof them has gripped the thread, the other disengages the thread-so thatonly one of the two devices is in gripping engagement with the thread-atsubstantially all times. this'manner have hithertobeen accepted assatisfactory, there nevertheless arises a danger, particularly when amachine incorporating such devices is run at relatively high speed, thatowing .to the rapiditywith'which the needle thread is handled by thevarious instrurnentalities of the machine, thread may steal through thatone of the two threadlocking-devices which is grippingthe thread at aparticular time or through both Blocking-devices at thetime when one iscoming into grippingengagement with the thread.

It is a further object of the present invention so to arrange'andactuate upper and lower thread locking devices arranged'respectivelybetween the supplyof needle thread and-the thread measuring device andbetween the measuring device and the stitch forming instrumentalities'that both locking devices are in gripping engagement with the needlethread simultaneouslythroughout substantial portions of a cycle of themachine, thus giving a more positive control of thethread. In theillustrative embodiment of the'present invention'hereinafterdescribedthis result is achieved by providing independent trains ofmechanism for actuating-each device separately and by actuthat bothdevices remain'in gripping engagement with the thread throughoutsubstantial portions of each machine cycle. V

In order that-the nature of the present invention maybe morefullyunderstood, the illustrative embodiment aforementioned will now bedescribed. I v

Figure 1 is a vertical sectional view illustrating the construction andrelative arrangement of some of the principal parts of a machineembodying the several features of the present invention; Figure '2 is asectional plan view of the machine illustrating particularly the shuttledriving mechanismgFigure 3 is an end" view showing certain l is a frontelevation, partly in section, of thread locking means according to'thepresent invention; Figure 5 is a-left-hand side elevation, partly-insection of part-of thelocking mechanism shown in Figure 4; Figure 6 is afront' elevation of a shuttle arrangement according to the presentinvention and thread handling devices of an outsole stitchingmachine'in,the relativepositions While thread locking devices operated in has beendrawn away from the shuttle; Figure 7 is a view similar to Figure 6 butwith the parts in the relative position they occupy when the loop ofneedle thread has been drawn down to the work; Figure 8 is a sectionalelevation of shuttle driving mechanism according to the presentinvention; Figure 9 is a plan View partly in section of some of theparts shown in Figure 8; Figures 10 and 11 are detail views of partsshown in Figures. 8 and 9; and Figures 12 to 23 inclusive arediagrammatic views illustrating the successive positions'taken by theshuttle, take-up, thread locks and pull-off during the formation of astitch.

The illustrative embodiment will be considered as comprising an outsolestitching machine which, except in so far as is hereinafter indicated,has thread handling instrumentalities and other cooperating memberssubstantially identical with and arranged to operate in the same manneras those of the machine disclosed in the specification of" applicationNo. 688,480. 7

The shuttle case i of the illustrative embodiment, while being of thesame general construction as the shuttle case of the machinedisclosed inapplication Serial No. 630,04ehas a bobbin case 3 mounted in it ofsomewhat different construction. The bobbin case 3 (and therefore thebobbin which it contains) is also mounted in the shuttle case'in'asomewhat difierent mannerfrom that of thebobbin case described in thespecification of'Patent No 1,991,456.

The bobbin case 3- of the illustrative embodiment isheldfrom completerotation with the shuttlecase by a fixed ridge engaging loosely in aV-shaped groove in the front wall of the bobbin againstthe outer face ofthe side wall of the bobbin case instead of being formed in the free endof the nose as described in Patent No. 1,991,456.

' Thus the exit hole i in the front wall of the bobbin case for theshuttle thread is, in-the present illustrative embodiment spaced onlyabout half Way between the-axis of the bobbin case and the free end ofthe nose. Thus, as the bobbin case vibrates to and fro during therunning of the machine, the amount of thread pulled off from the bobbindue'to the oscillations of the thread exit hole in the presentillustrative embodiment are substantially less than the-amounts pulledoff by the oscillations of the thread exit hole when the latter isformed in the end of the nose, as de-j scribed in Patent-N0. 1,991,456,and thus the variations in theslackness or tautness of the shuttlethread during the setting of successive stitch locks in the presentillustrative embodiment will 'be' substantially less than occur when abobbin case of the type disclosed in the application last 7' disclosedin Patent No. 1,991,456, this nose serves purely to prevent the shuttlethread, if for any reason it should becomeunduly slack, from bendingsofar rearwardly as to become liable to be caught by the beak 9 oftherotating shuttle. It willbe understood that, as in the case of theshuttle-referred to as'being described in Patent {shuttle case.

No. 1,991,456, the thread passes outwardly from the bobbin, through ahole in the side wall of the bobbin case and around the outside of thewall to the exit hole I in the nose which is close to the side wall ofthe bobbin case, the thread, as it passes between the hole in the sidewall of the bobbin case and the exit hole, passing through an adjustabletension device arranged on the outside of the side wall of the bobbincase.

The said thread exit hole 7 is so positioned on the bobbin case that itlies close to the lowest point on the bobbin case and substantially on aline drawn from the centre of the shuttle case to the needle hole in thework into which a stitch lock formed between the needle and shuttlethreads is being drawn by the tension on the needle thread during thesetting of a stitch.

:In the shuttle disclosed in Patent No. 1,991,456, the bobbin case ismounted in the shuttle case I in a housing which is concentric about theaxis ofthe shuttle case but in the shuttle of the illustrativeembodiment now being described the bobbin case 3 is mounted in theshuttle case I in a housing which is eccentric about the axis of the Forthis purpose the pin secured to the shuttle case is ofiset about threethirtyseconds of an inch from the axis of rotation of the shuttle case,the axis of the said pin lying on a line drawn from the axis of rotationof the shuttle case I to the forward end of the beak 9 of the shuttleand between the axis of rotation bin case concentrically with thelatter.

By arranging the bobbin case 3 eccentrically in the shuttle case I andby arranging the supporting pin for the bobbin case to be ofiset fromthe axis of the shuttle case along the particular direction abovementioned, certain desirable results hereinafter specified are achievedduring the formation and setting of a stitch, as will be apparent froman inspection of Figures 6 and 7 and Figures 12 to 23. The shuttle caseI of the illustrated machine is given two complete rotations at a varying speed during each stitch forming cycle, the connections for drivingthe shuttle (see Figs. 2 and 3) comprising oiTset shafts IE] and I2,cranks I4 and I 8' on the shafts and a connecting link I8. The shuttlecase is so arranged in the machine that as the setting of a stitch isbeing completed the beak 9 of the shuttle has passed through the lowestpoint in its path and is commencing to rise, the thread extending atthis time from the exit hole I in the bobbin case 3 to the work, lyingsubstantially in a plane which extends from the needle hole in the work,into which the shuttle thread is being drawn by the needle thread,through the axis of rotation of the shuttle case and also through theend of the shuttle beak and the axis of the pin which carries the bobbincase.

When the setting of the stitch has been substantially completedcontinued rotation of the shuttle case I, acting through the eccentricpin carrying the bobbin case 3, causes the bobbin case to lift bodilyand the stitch having been more or less completely set and, the needlethread still being under tension and therefore assisting in preventingthe thread look from being drawn upwardly out of the needle hole, causesa certain amount of thread to be drawn off the bobbin. When the shuttlecase has rotated through one hundred and eighty degrees from theposition last mentioned, the lifting of the bobbin case will, sinceit isoffset three thirty-seconds of an inch from the axis of the shuttlecase, have caused some three sixteenths of an inch of thread to bepulled off the bobbin against the action of the tension device on thebobbin case. As the beak of the shuttle case descends once more towardsits lowest position, the bobbin case will descend towards the work andwill pay out into the length of shuttle thread extending between thebobbin and the work the three sixteenths of an inch of thread which wasdrawn 01f the bobbin after the completion of the previous stitch settingoperation. The thread drawing-01f and paying out movements of the bobbincase just above mentioned will take place during the first half of eachstitch forming cycle of the machine but as, after the completion of thesetting of the previous stitch, no drawing down on to the work of theshuttle thread by the needle thread takes place until during the secondhaif of a stitch forming cycle (during which second half the shuttlemakes a further complete rotation) the paying out of the said portion ofshuttle thread during the first half of the cycle is idle.

As the shuttle rotates once more during the second half of the machinecycle, the shuttle beak 9 engages the loop of needle thread, held openfor it by the needle I I and thread lifter i3, and rises to lift thesaid loop over the shuttle. .As the shuttle beak rises, the bobbin case3 also rises bodily (due to its eccentric mounting in the shuttle case)and draws taut the slackened thread passing from the shuttle to thework. When the loop of needle thread has been lifted over the highestpart of the shuttle, the continued rotation of the shutle causes theshuttle beak 9 to commence to descend towards the work and causes thebobbin case 3 likewise to commence to descend towards the work. As theshuttle beak and bobbin case descend in unison towards the work, theloop of needle thread will be drawn down towards the work over theshuttle, and round the thread issuing therefrom, by the rotary take-updevice of the machine, which take-up device is the same in construction,arrangement, and operation as the take-up device disclosed inapplication Serial No. 688,480, and the bobbin case will once more berapidly paying out towards the work the amount of thread drawn off fromthe bobbin during the first half of the machine cycle. Thus the nearerthe shuttle beak approaches towards its lowest position and the furtherthe loop of needle thread is drawn down over the shuttle, the more slackwill the shuttle thread extending down to the work become. The loop ofneedle thread is actually pulled off the shuttle by the rotary take-updevice, some eighty to ninety degrees in the rotation of the shuttlebefore the shuttle beak again reaches the position it occupies when thenext stitch setting operation is completed and when the loop of needlethread is pulled oif the shuttle and into contact with the shuttlethread, which it straddles, the descending bobbin case will already havepaid ofi about half of the amount of thread pulled off the bobbin at theconclusion of the previous stitch forming cycle. The shuttle thread willtherefore already be in a slackened condition when it is engaged by theloop of needle thread and the latter can therefore commence to pull ittowards the work without causing any appreciable reeving of the twothreads together and without having to overcome substantial tensionexerted on the shuttle thread. As the loop of needle thread continues tobe pulled down towards ,the work by the take-up device, the bobbinmovesstill further downwardly andzpaysr-ofi still pulling the shuttlethread against the work to lay it on the latter practically the wholeamount of the thread pulled oil the. bobbin'after the conclusion of thelast stitch setting operation'x'willhave been paid out and'the threadpassingifrom the shuttle to the work willbe relatively slack;

Therefore as the needle thread continues to lay the shuttle thread on tothe work, which action takes place as the work is being. fed towards theshuttle by work clamping members of the machine, the slackened shuttlethread falls into a condition in which it can be easily'laid against thework without exercising any substantial tension on the needle threadandwithout'causing any appreciable reeving of the two threads together.The amount of thread pulled off the bobbin and paid out by the risingand falling bobbin is .of such alengtliii; e'. is three sixteenths'ofan. inch long as previously indicated) that when sewing stitches ofaverage length, all the slackness thrown into the shuttle thread in asingle cycle will have been used up in a single stitch formation or institch setting by'the end of the stitch setting operation.

ened as it is engaged by the needle thread and pulled down on to thework very small resistance will be offered by the shuttle thread-tobeing laid on the work, thus making for good stitch-making and avoidinguneven setting of the thread locks within the work.

Immediately after a setting of a stitch is completed thebobbin casewill, as above described, commence to riseto pull off thread from thebobbin for the formation of the next stitch.

In the machine disclosed'in prior application No. 688,480 the shuttle isarranged to be rotated ed in a cam-member rigidly secured to the upper;

end of the shaft, conical lower ends of which spring pressed piungersengage in depressions in theupper face of the spiral gear. Such an:arrangement was intended to couple the spiral gear normally to the shaftso that the gear rotates with the shaft but to allow the gear to remainstationary if for any reasonrotation of the shuttleshould be obstructed.This arrangement, while satisfactory when the machine runs at a moderatespeed, has been found at a relativelyhigh speed; not to provide asreliable a driving connection between the gear and shaft as is desiredand accordingly in the illustrative embodiment now being described, fourspring-pressed plungers l5 (Figures 8 and '11) are provided in the saidcam member l'l' the lower ends of which are bevelled to providechisel-like ends 19, the lengths of which lie radially of the verticalshaft. A ring 2l-secured E9 of the plungers l5 which are arranged toen-- gage within them. Since in the present illustrative embodiment fourspring-pressed plungers-l5 having chisel shaped lower ends ane arrangedto couple the gear2 3 to the vertical shaft- 759 2 a morepositivedriving connection between the gear and'ithis shaft is obtainedthereby guard-' ingefiectively'against relative slip occurring be tweenthe gear and the shaft during the normal operation-of, the machine whilestill allowing the V shaft to rotate relatively to the said gear if theshuttle should at any time becomejammed against. rotation. Relativelystrong springs 29 are provided above the spring pressed plungers l5 tomaintaintheir lower'ends pressed firmly in the grooves in the ringsecured to the said spiral gear.

As before stated, the shuttle is rotated twice each: cycle ofv themachine and it is necessary, in

order that the correct timing of the'shuttle in' theme-chine shall beregained if relative slip has:

occurred for any reason between the spiral gear? and the vertical shaft,that the said gear should until each plunger once more comes into linewith the same groove in the ring secured to the,

spiral gear as it engaged before the slip between the verticalshaft andthe spiral gear occurred or until-it comes into line with a groove lyingdia-- metrically opposite said groove. In order to ensure that the gear.23' will become coupled to the shaft 2'! only in one or: other of thesetwo-positions, two lugs M are formed on the outer edge of said ring 21and lie at the outer ends of two of the, grooves whichlie diametricallyopposite each other and two similar lugs 33 are formed on the inner edgeof the ring 2i and lie at the inner ends of the other two grooves. Eachof the two plungers which engage in the two grooves first abovementioned has an enlargement 35 formed on that'side of its lowerbevelled end 1 which lies nearer the axis ofthe said vertical shaft andeach of the other-two plungers which engage in the two grooves lastabove mentioned has an enlargement 31 formed on-that side of its lowerbevelled end which lies further from the axis of the vertical shaft. Thearrangement is such that if relative slip has occurred between therotary shaft 21 and the said gear 23, the lugs 33'formed onthe inneredge of the said ring will prevent the plungers l5, whichhaveenlargements 35 formed on their lower ends nearer to the axis ofthevertical shaft from entering the grooves adjacent these lugs butwill'allow those plung ers having enlargements 37 formed on the outersides of their lower ends to enter the saidgrooves. Similarly the lugs3i formed on the outer edge of the ring 2i while allowing those plungerswhich have enlargements 35 formed on the inner sides of their lower endsto enter the grooves will nevertheless prevent the plungers which haveenlargements 3! formed on their outer sides from en-- tering the groovesadjacent them. (As shown in Figures 10 and 11.)

Theillustrative embodiment is,like the machine disclosed in applicationNo. 688,480 provided with two thread locking devices arr'anged'one togrip the needle thread between the supply and a thread measuring deviceor pull-off and ,the other between the thread measuring device and thestitch 1 thread locking'devices'of the present illustrativeembodimentare: like the devices of the machine disclosed in the priorspecificationlast-referred measuring device and the stitch forminginstruto, in that that one (hereinafter termed the lower or rear threadlock) which engages the needle thread between the supply and the threadmeasuring device comprises a' relatively fixed thread-engaging plate ii(Figure 4) against which the thread is clamped by a cooperating plate &3which is moved yieldingly horizontally towards it and the other lockingdevice (hereinafter termed the upper or front thread lock) which engagesthe thread between the thread mentalities comprises a relatively fixedroll 45 over which the thread passes and a thread-engaging shoe 5? whichis arranged to be lowered towards the roll to press the thread againstthe upper face of the roll. In the present illustrative ,embodiment,however, two separate cam grooves are provided ina cam member 49 whichis secured to a driving sleeve for the rotary take-up deviceaforementioned and one of these cam grooves actuates a cam lever 5!which is coupled to the upper thread lock and the other cam grooveactuates a second cam lever 53 which is coupled to the lower threadlock, the connections from the two cam levers to their respective threadlocks being separate and unconnected so that the two locks are operatedindependently of each other. The movable member-of each of the threadlocks is moved yieldingly to grip the thread at certain times in themachine cycle against its cooperating stationary member through a springplunger arrangement 55 included in the.connections which connect it toits actuating cam lever but the movable members are arranged to be movedout of engagement withthe thread at the appropriate times in the machinecycle bya pin and slot connection 51 with the spring plunger which, whenthe spring behind the plunger, has

expanded to its original condition after the pressure of the movablemember of the thread lock on the thread has been released, causes themovable member to move positively somewhat away from its cooperatingfixed member, thus ensuring that actual separation of the cooperatingmembers occurs at the desired times in the machinecycle. In the case ofthe lower look, however, the movable member may be moved positively, i.e. unyieldingly, by its actuating mechanism and its cooperatingrelatively'fixed member 'may yield against a spring as the movablemember presses the thread against it. Such an arrangement tends tominimize the hammering action which the movable member exerts on thethread as it moves rapidly to grip the thread. The separate actuatingmechanism for the upper and lower, thread locks are arranged to act insuch time relation relatively to each other and to the'operation of thestitch forming instrumentalities of the machine that not only do boththread locks grip the thread simultaneously throughout relatively'longportions of the machine cycle during which there is a danger that threadmight steal through the looks but also each lock, considered separately,is caused to engage the thread at especially convenient times 1 in acycle of the machine.

The particular times in the machine cycle at which the two locks gripand release the needle thread independently will now be indicated. In

Referring to Figures 12 to 23 and assuming the machine to be inoperation sewing an outsole to a shoe and the stitch forminginstrumentalities to have reached the positions they occupied when themachine was at rest, the take-up roll 42 of the rotary take-up devicewill be commencing to set the thread lock of the stitch last formedwithin the work. At this time the lower thread lock is in grippingengagement with the needle thread, the upper thread lock being open atthis time but being ready to close. During the next few degrees ofrotation of the main shaft (e. g. during about twenty degrees ofrotation of the main shaft from its stopping position) the takeup rollwill have imparted the maximum tension to the needle thread stretchingthe latter somewhat during the final setting of the stitch and the upperthread lock will have been closed and will have firmly gripped thethread; the bottom lock still remaining closed. The take-up roll willhave imparted the maximum tension to the thread only just before theupper lock is firmly closed upon the thread and will preferably commenceto rise towards the work to pay out thread ready for the formation ofthe next stitch only after the upper lock actually has closed. The factthat the take-up roll will have imparted the maximum tension to thethread and will have stretched the thread before the upper lock closeswould give rise to the danger that when the take-up roll moves towardsthe work after having tensioned the thread, the tensioned thread, whichwill not instantaneously recover its unstretched condition, would, ifthe upper lock were open at that time, steal back somewhat through thetop lock thus rendering the next thread measuring operation inaccurateand producing inaccurated setting of the next thread look within thework. Since, however, the upper thread lock in the present illustrativeembodiment is caused to grip the thread almost immediately after thetake-up roll has imparted the maximum tension to the needle thread, thedanger of thread stealing back through the upper look as the takeup rollrises towards the work is either obviated or at least very substantiallyminimized. Since there is substantially no movement of the thread overthe stationary roll of the upper lock taking place when the upper lockcloses, there is no danger that reeving of the thread through the lockwill take place at that time. The upper lock grips the thread so soonafter the take-up roll has imparted the maximum tension to it that itgrips the thread while a considerable portion of this tension stillremains in the thread and therefore the portion of needle threadextending between the upper and lower locks is taut when the upper lockgrips the thread.

Both the upper and lower locks remain gripping the thread simultaneouslyuntil, when the take-up roll has risen somewhat towards the work and themachine shaft has rotated through about a hundred degrees from itsstopping position the thread measuring device, which comprises a rollindicated at 44 and which is constructed, arranged and actuated as inthe machine of application Serial No. 688,480, is ready to draw oil fromthe supply the necessary amount of needle thread for the formation ofthe next stitch. The lower look there upon opens, while the upper lockremains gripped on the thread, and remains open while the main shaft ofthe machine rotates through about a further hundred and thirty degrees,during which time the thread measuring device operates to pull thenecessary amount of thread from the supply through the open bottom lock.Just about this time the shuttle beak enters the loop of needle threadpulled upthrough the work by the needle, this pulling up of the needleloop being allowed by reason of the-rising of the take-up roll while theupperlock still remains closed. Immediately'afterthe thread-measuringdevice has completed its thread pulling off movement (1. e. when themain-shaft has rotated through two hundred and thirty degreesapproximately) the lower lock closes'and the thread pulled off thesupply by the measuring device remains locked between the upper andlower thread locking devices. Both the upper and lower locks remainsimultaneous- 1y gripping the thread until the main shaft has thenbecomes unlocked while the lo-werlockstill remains gripped upon thethread. The lower lock remains in gripping engagement with the needlethread throughout the remainder of the cycle and until, in the nextcycle, just before the threadmeasuring device operates once more to draw-ofi thread-from the supply.

Fromthe description'above given of the relative times in the machinecycle at which the upper and lower thread locks are respectively closedand-opened, it will be seen that between the time when the take-up rollimparts the maximumtensionto the thread and the time when the threadmeasuring device commences to pull off needle threadfrom the supply,both the upper and lower locks remain in gripping engagement with theneedle thread during arotation of the main shaft through about eightydegrees. It will further be seen that during the period of time thatelapses after the threadmeasuring device has pulled off the necessaryamount-of thread from the supply but before the take-up roll imparts themaximum tension to the thread,both locks will remain in grippingengagement with the thread'during about a rotation of the main shaftthrough about sixty-five degrees. Since the lower lock does not closeuntil after the thread measuring device has concluded its thread-pullingoff function, at which time the upper lock is closed, no movement of thethread through'the lower lock is taking place as the lower lock closesand therefore objectionable reeving of the thread through the closinglock is obviated. Since thetwo locks'are simultaneously in grippingengagement with the 'thread-throughoutrelatively large portions of thecycle each lock will have ample time to settle itself firmly on thethread before the other lock opens.

It will be appreciated that if the movable members of the upper andlower locks were always moved, towards their cooperating stationarymembers-to grip the'thread between them from constant positions awayfrom the stationary mem bers whatever the thickness of the needle threadnotronly would the intensity of the gripping ac tion of the locks on thethread vary with threads of different thicknesses but also the spaceprovidedbetweenthe movable and stationary memrelatively thick one.

bers of the locks when-the'latter are open would "be greater than isnecessary when the needle thread is a relatively fine one and might beless 1 than is desirable when the needle, thread is a V In order that auniform 5 clearance may be. provided between the thread, whatever thethickness of the latter, 'and'the thread engaging members of the lookswhen the latter are open and also inorder that the precise times in themachine cycle at which the locks actually grip'the thread may be thesame for all thicknesses of thread, an eccentric setting is providedfor-the movable member of eachlock byadjustment of which theposition.from;.which the movable member starts to move'towards itscooperating stationary member can be adjusted without disturbing thetimes at which the movable member nism.

The eccentric settingfor the upper thread lock comprises a .sleeve 5.9rotatably mounted in a bearing in abracket 61. 'The sleeve 59 haseccentrically mounted in it a spindle 6.3 rotation of which moves thethread-engaging shoe 4'! to-,

'wards or from the fixed roll 45. The sleeve 592 has extending from-itan arm 65 having formed in ita slot '61 through which passes a screw '69threaded into "the bracket '6 I. i691isslackened, the sleeve 59 may be.rotated by means of the arm 65 to adjust the shoe 4.! towards t or,from the roll 45. The eccentric setting of the lower. threadelockcomprises a studtlLwhich is secured in thecam lever 53 and having aneccentrio portion 73 on which is mounted acam roll 15 engaging inone ofthe cam grooves inthe cam block 49. .By rotating the stud H, the plate'43 may be adjusted towards or from the plate 4|.v

' .As inthe caseofthe machine disclosedin prior :applicationNo,688,480,.themachine of the i11ustrative embodiment comeslto a stopwhile theam lower thread lock is closed upon-the thread and mechanismconnected to the'stop motion of the machine and similar to thatdescribed in that application isembodied in the machine of the-pies-..-ent illdstrative embodiment to open the lower thread look when themachine stops to allow the operator to draw through it inremovingthework from the machine: The said mechanism com-v prises an eccentricsleeve 11 on which the cam,

lever 53is=pivoted." The sleeve 11 is pivotedon" a pin l9'secured inbearings '81, 8| extending from the bracket BI and has extending from it.an arm 83 which is connected by a pin and slot "connection to a' rod85. The rod "85 is connected? "to"abell-crank'leverill which isconnected by a 1 rod "89 to the said stop motion of the machine.

The sleeve 71 also hasextending from it an arm 1 ill to which isconnected one endof a spring 93 the other end of which is connected tothe machine frame. When the clutch controlling treadle of the machine isdepressed to start the machine,

the spring'93 is allowed to swing theeccentric sleeve-17 in ananti-clockwise direction, as viewed in Fig'ure l, until the arm 83engages a plate 95 5 5 secured on one of the-bearingstl. Movement of theeccentric sleeve 17in this direction swings the cam lever 53 abouttheaxis of. the cam roll '15 and moves the plate 43 towards the plate 4|into a position from which it can be moved by the aft cam lever 53 whenit is aotuatediby its cam at the appropriate time in the machine cycletowards the plate 4! to grip, the thread. As'the is actuated by itsoperating mecha- 7 When the screw machine comes to rest, the eccentricsleeve 11 is} swung in the opposite direction and causes the -7pendently of the lower lock, it may, if desired,

be arranged to grip the thread somewhat earlier in the machine cyclethan above set forth in order that the upper and lower thread locks mayboth be gripping the thread just previous to and during the time thatthe take-up device is imparting the maximum tension to the needle threadduring the setting of the stitch so that greater resistance to drawingof the thread through the looks at this time may be secured. If,however, the upper lock is arranged to grip the needle thread somelittle time before the take-up device imparts the maximum stretchsetting tension to the needle thread, it will happen that when themachine comes to a stop not only will the lower lock be gripping thethread, but the upper lock will also be gripping the thread andconsequently it will be necessary to include in the machine mechanismwhich may be similar to that for opening the lower look when the machinestops, for opening also the upper'lock at this time.

The nature and scope of the invention having been indicated, and amachine embodying the several features of the invention having beenspecifically described, what is claimed is:

1. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, a shuttle, a take-up, a pull-off, a frontthread lock between the take-up and pull-01f, a rear thread lock betweenthe pull-off and the supply, and means for actuating the parts to causethe take-up to set the stitch while the rear thread lock is closed andto close the front thread look while the thread is being strained by thetake-up.

2. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, a shuttle, a take-up, a pull-off, a frontthread lock between the take-up and pull-01f, a rear thread lock betweenthe pull- 01f and the supply, and means for actuating the parts to causethe pull-off to pull thread from the supply while the front thread lockis closed and while the rear thread lock is open, and to maintain thefront thread lock closed until the needle looprear thread lock betweenthe pull-off and the supply, and means for actuating the parts to causethe take-up to set the stitch while the rear thread lock is closed, toclose the front thread look while the thread is being strained by thetake-up, to cause the pull-01f to pull thread from the supply while thefront thread lock is closed and while the rear thread lock is open, andto maintain the front thread lock closed until the needle loop passesover the top of the shuttle.

4. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, a shuttle, a take-up, a pull-off, a frontthread lock between the take-up and pull-01f, a rear thread lock betweenthe pull-off and the supply, and means for actuating the parts to causethe take-up to set the stitch while the rear lock is closed and whilethe front lock is open and to cause the pull-off to pull thread from thesupply while the front lock is closed and while the rear lock is open,and means for varying the time during the stitch forming cycle at whichthe locks are actuated.

5. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a hook needle, a discoidal shuttle having a looptaking 5 beak and a thread case mounted in the shuttle provided with anopening for the passage of the shuttle thread from the thread case tothe Work and formed with a radially projecting nose extending beyond thethread opening into a position to hold the shuttle thread out of thepath of the shuttle beak. v

6. Alockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, a shaft making one rotation during each1'5stitch forming cycle, a gear on the shaft, a rotary shuttle driven fromsaid gear and a slip driving connection between the gear and the shaftcomprising a plurality of spring plungers mounted on the shaft andprovided with chisel-like ends en- "20 gaging radial grooves in thegear.

7. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, ashaft making one rotation during eachstitch forming cycle, a gear on the shaft, a multiple rotary shuttledriven from said gear, a slip driving connection between the gear andthe shaft comprising a plurality of spring plungers mounted on the shaftand arranged to engage at their ends with equally spaced recesses in thegear, and means acting during the relative rotary movement of the shaftand gear to permit engagement of each plunger with a portion only ofsaid recesses.

8. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, a shaft making one rotation during eachstitch forming cycle, a gear on the shaft, a twoto-one rotary shuttledriven from said gear, a slip driving connection between the gear andthe shaft comprising four spring plungers mounted on the shaft andprovided with chisel-like ends engaging equally spaced radial grooves onthe gear, and means acting during a relative rotary movement of theshaft and gear to permit engagement of each plunger with diametricallyopposite grooves only.

9. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a needle, a shaft making one rotation during eachstitch forming cycle, a gear on the shaft, a multiple rotary shuttledriven from said gear, a slip driving connection between the gear andthe shaft comprising a plurality of spring pressed plungers mounted onthe shaft and arranged to engage at their ends with recesses in thegear, and lugs on the shaft cooperating with the plungers during arelative rotary movement of the shaft and gear to permit engagement ofeach plunger with a portion only of said recesses.

10. A lockstitch sewing machine having, in combination, stitch formingdevices comprising a hogked needle, a take-up acting during each stitchforming cycle to pull a loop of needle thread from the shuttle and setthe stitch, a ro- 65 tating discoidal shuttle, means actuated by therotation of the shuttle to pull off and give up shuttle thread, andmeans for rotating the shuttle in timed relation to the take-up to causethread to be pulled from the shuttle after a stitch has been set by thetake-up and while tension is being exerted on the set stitch by thetake-up and to give up thread while the next needle loop is being drawnfrom the shuttle into the work by the take-up.

11. A lockstitch sewing machine having in combination, stitch formingdevices comprising a hooked needle, a take-up acting during each "stitchforming cycle to pull a loop of needle thread from the shuttle and setthe stitch, a rotating discoidal shuttle, a none-rotating bobbin casemounted eccentrically in the shuttle acting to pull off and give upshuttle thread during the rotation of the shuttle, and means forrotating the shuttle in timed relation to the taker-up to cause threadto be pulled from the shuttle after a stitchhas been set by the take-upand while'tension is being exerted on the set stitch by the take-up andto give up thread while the next needle loop is 'being drawn from theshuttle into the Work by the take-up. 12. A lockstitch sewing machinehaving, 1 combination, stitch forming devices vcomprising a hookedneedle, a take-up, a rotating discoidal shuttle, means for imparting aplurality of rotations to the shuttleduring each stitch form- 'ingcycle, and means actuated by the shuttle during onerrotation to pullthread from the shuttle after a stitch has been set by the take-upcombination, stitch forming devices comprising a hooked needle, atake-up, a rotating discoidal shutt1e,'a non-rotatingbobbin case mountedeccentrically in the shuttle acting to pull off and give up thread, andmeans for imparting a plurality of rotations to the'shuttle during eachstitch forming cycle in timed' relation to the takeup to cause thread tobe pulled from the shuttle during one rotation after a stitch has beenset by thetake-up and while tension is being exerted.

on a set stitch: by the take-up and to give up thread during asubsequent rotation of the shuttle while the next needle loop is beingdrawn from the shuttle into the work by the take-up.

V JOSEPH GOULDBOURNf 1 HAROLD ERNEST ELLIOTT. NATHAN FREEMAN HOPKINS.

